CN102857292A - Multi-user bidirectional relay transmission system and multi-user bidirectional relay transmission method - Google Patents

Abstract

The invention discloses a multi-user bidirectional relay transmission system and a multi-user bidirectional relay transmission method. The method comprises the following steps that: each user side simultaneously transmits a transmission signal to be transmitted to a relay node at a first time slot; the relay node receives the signals, multiplies the signals with a pre-coding matrix, and broadcasts a product to all user terminals at a second time slot; the each user side receives the pre-coded signals; each user terminal carries out self-interference elimination on the received signals; and the each user terminal carries out signal demodulation on the received signals subjected to the self-interference elimination. According to the multi-user bidirectional relay transmission system and the multi-user bidirectional relay transmission method, the spectrum effectiveness is improved by adopting a bidirectional relay protocol, and meanwhile, the relay node is subjected to pre-coding design, so that the performance of the system is improved.

Description

Multi-user's bi-directional relaying transmission system and method

Technical field

The present invention relates to wireless communication technology field, particularly relate to a kind of multi-user's bi-directional relaying transmission system and method that realizes a plurality of user's transmitted in both directions with the bi-directional relaying host-host protocol.

Background technology

In the multi-user transmission network, it is comparatively common that a plurality of users carry out the scene of information exchange simultaneously.Yet, because disturbing, complicated wireless transmission environment and multi-user transmission exist, the performance of each user's receiving terminal often is difficult to guarantee.This phenomenon is particularly outstanding in the larger wireless network of transmission space span.Thus, various anti-fading, Anti-Jamming Techniques constantly are suggested.

Wherein a kind of effective solution is to use via node in transmission link, to assist original end-to-end transmission.This wireless transmission scheme based on via node has solved the transmission reliability problem well.But consider the realizability of equipment, this via node often can only be operated in semiduplex mode, i.e. the transmitting-receiving of via node operation can only be operated in different time slots.This unidirectional relay transmission mode causes the spectrum efficiency of system to reduce inevitably.

Summary of the invention

The deficiency that exists for overcoming above-mentioned prior art, the present invention's purpose is to provide a kind of multi-user's bi-directional relaying transmission system and method, and it uses the bi-directional relaying agreement to improve spectrum efficiency based on the bi-directional relaying agreement, simultaneously via node is carried out Precoding Design, to improve the performance of system.

For reaching above-mentioned and other purpose, the invention provides a kind of multi-user's bi-directional relaying transmission system, be used for multi-user's end and carry out bi-directional exchanges of information, comprise at least:

A plurality of user sides, each user side comprises transmission module, reception module, self-interference elimination module and demodulation module at least, the transmission module of each user side sends to via node with signal to be transmitted simultaneously in the first time slot, this receives module and is used for receiving the signal of this via node after precoding, this self-interference is eliminated module and is used for carrying out to the received signal the self-interference elimination, and this demodulation module is used for the signal after the self-interference elimination is carried out demodulation; And

Via node, at least comprise that signal to be transmitted receives module, precoding module and broadcasting module, this signal to be transmitted receives module and is used for receiving the signal to be transmitted that each user side sends simultaneously, the reception signal times that this precoding module will receive is carried out precoding with pre-coding matrix, and the reception signal of this broadcasting module after the second time slot is with precoding is broadcast to each user side.

Further, this pre-coding matrix is:

$F=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\δ}}_k{t}_k^b{t}_k^{\mathrm{mH}}=T_b\mathrm{\Δ}{T}_m^H,$

Wherein,

Δ=Diag (δ ₁, δ ₂..., δ _K), δ _kBe power division parameter, T _bFor with user side to the relevant matrix of the channel vector of via node, T _mFor with via node to the relevant matrix of the channel vector of user terminal.

Further, each user side is only installed an antenna, and the antenna number of this via node is M, and M 〉=2K-1, and K is that the user is to number.

Further, this self-interference is eliminated module the signal that receives is carried out the self-interference elimination, deducts coding self-interference item.

For reaching above-mentioned and other purpose, the present invention also provides a kind of multi-user's bi-directional relaying transmission method, comprises the steps:

Step 1, each user side sends to via node with signal to be transmitted simultaneously in the first time slot;

Step 2, this via node with a pre-coding matrix, then is broadcast to all user terminals in the second time slot with the signal times that receives;

Step 3, each user side receives the signal through precoding;

Step 4, each user terminal are carried out self-interference to the signal that receives and are eliminated; And

Step 5, each user terminal carries out the signal demodulation to the reception signal after eliminating through self-interference.

Further, this pre-coding matrix is:

$F=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\δ}}_k{t}_k^b{t}_k^{\mathrm{mH}}=T_b\mathrm{\Δ}{T}_m^H,$

Wherein,

Δ=Diag (δ ₁, δ ₂..., δ _K), δ _kBe power division parameter, T _bFor with user side to the relevant matrix of the channel vector of via node, T _mFor with via node to the relevant matrix of the channel vector of user terminal.

Further, make up parameter

Comprise the steps:

At first make up ${\hat{H}}_k=[{\tilde{H}}_1,{\tilde{H}}_2,...,{\tilde{H}}_{k-1},{\tilde{H}}_{k+1},...,{\tilde{H}}_K]=\left[U_{{\hat{H}}_k}^{\left(1\right),}{U}_{{\hat{H}}_k}^{\left(0\right)}\right]{\mathrm{\Σ}}_{{\hat{H}}_k}{V}_{{\hat{H}}_k}^H,$ Wherein,

For The kernel vector, h _1k, h _2kBe user side S _1k, S _2kChannel vector to via node;

Secondly make up $[u_{h_k}^{\left(1\right)},U_{h_k}^{\left(0\right)}]{\mathrm{\Σ}}_{h_k}{V}_{h_k}^H=U_{{\hat{H}}_k}^{\left(0\right)H}{h}_k;$

Utilize at last With

Make up

$t_k^m=U_{H_k}^{\left(0\right)}{u}_{h_{1k}}^{\left(1\right)}.$

Further, make up parameter

Structure comprises the steps:

At first make up ${\hat{G}}_k={[{\tilde{G}}_1,{\tilde{G}}_2,...,{\tilde{G}}_{k-1},{\tilde{G}}_{k+1},...,{\tilde{G}}_K]}^T=U_{{\hat{G}}_k}{\mathrm{\Σ}}_{{\hat{G}}_k}{[V_{{\hat{G}}_k}^{\left(1\right)},V_{{\hat{G}}_k}^{\left(0\right)}]}^H,$

For Kernel, g _1k, g _2kFor via node arrives user side S _1k, S _2kChannel vector;

Secondly make up $U_{g_k}{\mathrm{\Σ}}_{g_k}{[v_{g_k}^{\left(1\right)},V_{g_k}^{\left(0\right)}]}^H=g_k^T{V}_{{\hat{G}}_k}^{\left(0\right)};$

Make up at last $t_k^b=V_{{\hat{G}}_k}^{\left(0\right)}{v}_{g_k}^{\left(1\right)}.$

Further, power division parameter δ _kMethod for solving comprise the steps:

Step 1 is established t _Max=min _{J, k}c _Jk/ d _Jk, t _Min=0;

Step 2, order $\hat{t}=\frac{t_{\max }+t_{\min }}{2};$

Step 3, solving-optimizing,

Step 4 is if following formula is found the solution the value that obtains less than P _R, then

Otherwise, establish

Step 5 jumps to step 3, until t _Max-t _MinLess than 0.01.

Further, in step 4, each user terminal deducts distracter with the signal that receives.

Compared with prior art, the present invention's a kind of multi-user's bi-directional relaying transmission system and method are by using bi-directional relaying, at the first time slot, multiple users sends to via node simultaneously with signal to be transmitted, by via node signal and the pre-coding matrix that receives multiplied each other, and then second time slot broadcasted, reduced the decline between the user, because transmitted in both directions is finished by 2 time slots, improved the availability of frequency spectrum of system, simultaneously the present invention has further promoted systematic function also by the design of precoding.

Description of drawings

Fig. 1 is the system architecture diagram of a kind of multi-user's bi-directional relaying of the present invention transmission system;

Fig. 2 is the schematic diagram of the preferred embodiment of a kind of multi-user's bi-directional relaying of the present invention transmission system;

Fig. 3 is the flow chart of steps of a kind of multi-user's bi-directional relaying of the present invention transmission method.

Embodiment

Below by specific instantiation and accompanying drawings embodiments of the present invention, those skilled in the art can understand other advantage of the present invention and effect easily by content disclosed in the present specification.The present invention also can be implemented or be used by other different instantiation, and the every details in this specification also can be based on different viewpoints and application, carries out various modifications and change under the spirit of the present invention not deviating from.

Fig. 1 is the system architecture diagram of a kind of multi-user's bi-directional relaying of the present invention transmission system.As shown in Figure 1, a kind of multi-user's bi-directional relaying of the present invention transmission system based on the bi-directional relaying host-host protocol, is used for each user side and carries out two-way information exchange, and it comprises at least: a plurality of user sides 10 and via node 11.

Wherein each user side 10 all comprises transmission module 101, reception module 102, self-interference elimination module 103 and demodulation module 104 at least, and transmission module 101 is used for each user side 10 and simultaneously signal to be transmitted is sent to via node 11 in the first time slot; Receive module 102 and be used for receiving the signal of via node 11 after precoding; Self-interference is eliminated module 103 and is used for carrying out to the received signal the self-interference elimination, deducts coding self-interference item; Demodulation module 104 is used for the signal after the self-interference elimination is carried out demodulation.

Via node 11 comprises that at least signal to be transmitted receives module 110, precoding module 111 and broadcasting module 112, and signal to be transmitted receives module 110 and is used for receiving the signal to be transmitted that each user side sends simultaneously; The reception signal times that precoding module 111 will receive is carried out precoding with pre-coding matrix; 112 reception signals after the second time slot is with precoding of broadcasting module are broadcast to each user side 10.

Fig. 2 is the schematic diagram of the preferred embodiment of a kind of multi-user's bi-directional relaying of the present invention transmission system.Below will cooperate Fig. 2 to further specify the present invention.In preferred embodiment of the present invention, user S _1kNeed and user S _2kCarry out two-way information exchange, k=1 here, 2 ..., K, K are that the user is to number.The antenna number of via node is M, and M 〉=2K-1.Each user side is only installed an antenna.All user S _1kWith user S _2kThe transmission module 101 of terminal sends to via node 11 with signal to be transmitted simultaneously, and the signal that the signal reception module 110 to be transmitted of via node 11 receives can be expressed as

Here s _JkBe user S _JkThe signal that sends, and its power is P _Jkh _JkBe user S _JkTo the channel vector of via node, n _RBe the reception noise of via node, its average is 0, and covariance matrix is

The precoding module 111 of via node 11 will receive signal y _RBe multiplied by pre-coding matrix F, then utilize broadcasting module 112 to be broadcast to all user terminals.Broadcast singal can be characterized by x _R=Fy _REach user terminal S _JkThe signal that receives of reception module 102 can be characterized by ${\tilde{y}}_{\mathrm{jk}}=\underset{l=1}{\overset{K}{\mathrm{\Σ}}}{g}_{\mathrm{jk}}^T{\mathrm{Fh}}_{\stackrel{\‾}{j}l}{s}_{\stackrel{\‾}{j}l}+\underset{l=1}{\overset{K}{\mathrm{\Σ}}}{g}_{\mathrm{jk}}^T{\mathrm{Fh}}_{\mathrm{jl}}{s}_{\mathrm{jl}}+g_{\mathrm{jk}}^T{\mathrm{Fn}}_R+n_{\mathrm{jk}},$ Here g _JkFor via node arrives user terminal S _JkChannel vector.n _JkBe user terminal S _JkThe reception noise, and its noise is 0, covariance is

Each user terminal S _JkThe self-interference signal of eliminating 103 pairs of receptions of module carry out self-interference and eliminate, deduct coding self-interference item

The reception signal that obtains can be characterized by $y_{\mathrm{jk}}=g_{\mathrm{jk}}^T{\mathrm{Fh}}_{\stackrel{\‾}{j}k}{s}_{\stackrel{\‾}{j}k}+\underset{l\≠k}{\mathrm{\Σ}}\left(g_{\mathrm{jk}}^T{{\mathrm{Fh}}_{\stackrel{\‾}{j}l}{s}_{\stackrel{\‾}{j}l}+g}_{\mathrm{jk}}^T{\mathrm{Fh}}_{\mathrm{jl}}{s}_{\mathrm{jl}}\right)+g_{\mathrm{jk}}^T{\mathrm{Fn}}_R+n_{\mathrm{jk}},$ And finally utilize demodulation module 104 to carry out to received signal the signal demodulation.

Fig. 3 is the flow chart of steps of a kind of multi-user's bi-directional relaying of the present invention transmission method.As shown in Figure 3, a kind of multi-user's bi-directional relaying of the present invention transmission method comprises the steps:

Step 301, each user side sends to via node with signal to be transmitted simultaneously in the first time slot.

In preferred embodiment of the present invention, suppose user S _1kNeed and user S _2kCarry out two-way information exchange, k=1 here, 2 ..., K, K be the user to number, the antenna number of via node is M, and M 〉=2K-1.Each user side is only installed an antenna.The signal that receives of via node can be expressed as so

Here s _JkBe user S _JkThe signal that sends, and its power is P _Jkh _JkBe user S _JkTo the channel vector of via node, n _RBe the reception noise of via node, its average is 0, and covariance matrix is

Step 302, via node is with the signal y that receives _RMultiply by pre-coding matrix F, then be broadcast to all user terminals in the second time slot, broadcast singal can be characterized by x _R=Fy _R

Step 303, each user side receives the signal through precoding, user terminal S _JkThe signal that receives can be characterized by

Here g _JkFor via node arrives user terminal S _JkChannel vector.n _JkBe user terminal S _JkThe reception noise, and its noise is 0, covariance is

Step 304, each user terminal S _JkThe signal that receives is carried out self-interference eliminate, deduct coding self-interference item

The reception signal that obtains can be characterized by

$y_{\mathrm{jk}}=g_{\mathrm{jk}}^T{\mathrm{Fh}}_{\stackrel{\‾}{j}k}{s}_{\stackrel{\‾}{j}k}+\underset{l\≠k}{\mathrm{\Σ}}\left(g_{\mathrm{jk}}^T{\mathrm{Fh}}_{\stackrel{\‾}{j}l}{s_{\stackrel{\‾}{j}l}+g}_{\mathrm{jk}}^T{\mathrm{Fh}}_{\mathrm{jl}}{s}_{\mathrm{jl}}\right)+g_{\mathrm{jk}}^T{\mathrm{Fn}}_R+n_{\mathrm{jk}}.$

Step 305, each user terminal carries out the signal demodulation to the reception signal after eliminating through self-interference.

Below will the method for designing of the pre-coding matrix F of the via node in the step 302 be further specified, in preferred embodiment of the present invention, the design of pre-coding matrix F is finished by following two concrete steps:

The first step, the concrete structure of structure pre-coding matrix F, it specifically can be expressed as:

Here $T_b=[t_1^b,t_2^b,\·\·\·,t_K^b],$ $T_m=[t_1^m,t_2^m,\·\·\·,t_K^m],$ Δ=Diag(δ ₁,δ ₂,…,δ _K)。

δ wherein _kBe the power division parameter, will be optimized at second step.Design parameter

Make up as follows Here

With

Obtain from following steps respectively: at first make up ${\hat{H}}_k=[{\tilde{H}}_1,{\tilde{H}}_2,...,{\tilde{H}}_{k-1},{\tilde{H}}_{k+1},...,{\tilde{H}}_K]=\left[U_{{\hat{H}}_k,}^{\left(1\right)}{U}_{{\hat{H}}_k}^{\left(0\right)}\right]{\mathrm{\Σ}}_{{\hat{H}}_k}{V}_{{\hat{H}}_k}^H,$ Here ${\tilde{H}}_k=[h_{1k},h_{2k}],$

For

The kernel vector.Secondly make up $[u_{h_k}^{\left(1\right)},U_{h_k}^{\left(0\right)}]{\mathrm{\Σ}}_{h_k}{V}_{h_k}^H=U_{{\hat{H}}_k}^{\left(0\right)H}{h}_{k.}$ The final utilization

With

Make up

As above.Similar, for

Construction step is as follows.At first ${\hat{G}}_k={[{\tilde{G}}_1,{\tilde{G}}_2,...,{\tilde{G}}_{k-1},...,{\tilde{G}}_K]}^T=U_{{\hat{G}}_k}{\mathrm{\Σ}}_{{\hat{G}}_k}{[V_{{\hat{G}}_k}^{\left(1\right)},V_{{\hat{G}}_k}^{\left(0\right)}]}^H,$ Here

For

Kernel.Secondly make up $U_{g_k}{\mathrm{\Σ}}_{g_k}{[v_{g_k}^{\left(1\right)},V_{g_k}^{\left(0\right)}]}^H=g_k^T{V}_{{\hat{G}}_k}^{\left(0\right)}.$ Make up at last $t_k^b=V_{{\hat{G}}_k}^{\left(0\right)}{v}_{g_k}^{\left(1\right)}.$

Because the required solution of above-mentioned via node pre-coding matrix comprises δ _kThe power division problem, the below provides concrete method for solving.This problem is for finding the solution following optimization problem

max _Δ,t?t

$s.t.\frac{{\mathrm{\δ}}_k^2{c}_{\mathrm{jk}}}{{\mathrm{\δ}}_k^2{d}_{\mathrm{jk}}+{\mathrm{\σ}}_{\mathrm{jk}}^2}\≥t,\∀j,k$

Δ ^T(K⊙L ^T)Δ≤P _R

Here ⊙ is the operation of matrix dot product.This optimization can be found the solution by following iterative process, and it is as follows that concrete iteration is crossed car:

1, establishes t _Max=min _{J, k}c _Jk/ d _Jk, t _Min=0;

2、 $\hat{t}=\frac{t_{\max }+t_{\min }}{2}$

3, solving-optimizing

min _ΔΔ ^T(K⊙L ^T)Δ

4、 $s.t.{\mathrm{\δ}}_k\≥\sqrt{\left({\mathrm{\σ}}_{\mathrm{jk}}^2\hat{t}\right)/(c_{\mathrm{jk}}-d_{\mathrm{jk}}\hat{t})},\∀j,k$

If 5 following formulas are found the solution the finger that obtains less than P _R, then

Otherwise, establish

Jumped to for the 3rd step, until t _Max-t _MinLess than 0.01.

In sum, the present invention's a kind of multi-user's bi-directional relaying transmission system and method are by using bi-directional relaying, at the first time slot, multiple users sends to via node simultaneously with signal to be transmitted, by via node signal and the pre-coding matrix that receives multiplied each other, and then second time slot broadcasted, reduced the decline between the user, because transmitted in both directions is finished by 2 time slots, improved the availability of frequency spectrum of system, simultaneously the present invention has further promoted systematic function also by the design of precoding.

Above-described embodiment is illustrative principle of the present invention and effect thereof only, but not is used for restriction the present invention.Any those skilled in the art all can be under spirit of the present invention and category, and above-described embodiment is modified and changed.Therefore, the scope of the present invention should be listed such as claims.

Claims (10)

1. multi-user's bi-directional relaying transmission system is used for multi-user's end and carries out bi-directional exchanges of information, comprises at least:

A plurality of user sides, each user side comprises transmission module, reception module, self-interference elimination module and demodulation module at least, the transmission module of each user side sends to via node with signal to be transmitted simultaneously in the first time slot, this receives module and is used for receiving the signal of this via node after precoding, this self-interference is eliminated module and is used for carrying out to the received signal the self-interference elimination, and this demodulation module is used for the signal after the self-interference elimination is carried out demodulation; And

Via node, at least comprise that signal to be transmitted receives module, precoding module and broadcasting module, this signal to be transmitted receives module and is used for receiving the signal to be transmitted that each user side sends simultaneously, the reception signal times that this precoding module will receive is carried out precoding with pre-coding matrix, and the reception signal of this broadcasting module after the second time slot is with precoding is broadcast to each user side.

2. multi-user's bi-directional relaying transmission system as claimed in claim 1, it is characterized in that: this pre-coding matrix is:

$F=\underset{K=1}{\overset{k}{\mathrm{\Σ}}}{\mathrm{\δ}}_K{t}_k^b{t}_k^{\mathrm{mH}}=T_b\mathrm{\Δ}{T}_m^H,$

Wherein,

Δ=Diag (δ ₁, δ ₂..., δ _K, δ _kBe power division parameter, T _bFor with user side to the relevant matrix of the channel vector of via node, T _mFor with via node to the relevant matrix of the channel vector of user terminal.

3. multi-user's bi-directional relaying transmission system as claimed in claim 1, it is characterized in that: each user side is only installed an antenna, and the antenna number of this via node is M, and M 〉=2K-1, and K is that the user is to number.

4. multi-user's bi-directional relaying transmission system as claimed in claim 1 is characterized in that: this self-interference is eliminated module and the signal that receives is carried out self-interference is eliminated, and deducts coding self-interference item.

5. multi-user's bi-directional relaying transmission method comprises the steps:

Step 1, each user side sends to via node with signal to be transmitted simultaneously in the first time slot;

Step 2, this via node with a pre-coding matrix, then is broadcast to all user terminals in the second time slot with the signal times that receives;

Step 3, each user side receives the signal through precoding;

Step 4, each user terminal are carried out self-interference to the signal that receives and are eliminated; And

Step 5, each user terminal carries out the signal demodulation to the reception signal after eliminating through self-interference.

6. multi-user's bi-directional relaying transmission method as claimed in claim 5, it is characterized in that: this pre-coding matrix is:

$F=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\δ}}_k{t}_k^b{t}_k^{\mathrm{mH}}=T_b\mathrm{\Δ}{T}_m^H,$

Wherein,

Δ=Diag (δ ₁, δ ₂..., δ _K), δ _kBe power division parameter, T _bFor with user side to the relevant matrix of the channel vector of via node, T _mFor with via node to the relevant matrix of the channel vector of user terminal.

7. multi-user's bi-directional relaying transmission method as claimed in claim 6 is characterized in that, makes up parameter Comprise the steps:

At first make up ${\hat{H}}_k=[{\tilde{H}}_1,{\tilde{H}}_2,...,{\tilde{H}}_{k-1},{\tilde{H}}_{k+1},...,{\tilde{H}}_K]=[U_{{\hat{H}}_k}^{\left(1\right)},U_{{\hat{H}}_k}^{\left(0\right)}]{\mathrm{\Σ}}_{{\hat{H}}_k}{V}_{{\hat{H}}_k}^H,$ Wherein,

For

The kernel vector, h _1k, h _2kBe user side S _1k, S _2kChannel vector to via node;

Secondly make up $[u_{h_k}^{\left(1\right)},U_{h_k}^{\left(0\right)}]{\mathrm{\Σ}}_{h_k}{V}_{h_k}^H=U_{{\hat{H}}_k}^{\left(0\right)H}{h}_k;$

Utilize at last

With

Make up

$t_k^m=U_{H_k}^{\left(0\right)}{u}_{h_{1k}}^{\left(1\right)}.$

8. multi-user's bi-directional relaying transmission method as claimed in claim 6 is characterized in that, makes up parameter

Structure comprises the steps:

At first make up ${\hat{G}}_k={[{\tilde{G}}_1,{\tilde{G}}_2,...,{\tilde{G}}_{k-1},{\tilde{G}}_{k+1},...,{\tilde{G}}_K]}^T=U_{{\hat{G}}_k}{\mathrm{\Σ}}_{{\hat{G}}_k}{[V_{{\hat{G}}_k}^{\left(1\right)},V_{{\hat{G}}_k}^{\left(0\right)}]}^H,$

For

Kernel, g _1k, g _2kFor via node arrives user side S _1k, S _2kChannel vector;

Secondly make up $U_{g_k}{\mathrm{\Σ}}_{g_k}{[v_{g_k}^{\left(1\right)},V_{g_k}^{\left(0\right)}]}^H=g_k^T{V}_{{\hat{G}}_k}^{\left(0\right)};$

Make up at last $t_k^b=V_{{\hat{G}}_k}^{\left(0\right)}{v}_{g_k}^{\left(1\right)}.$

9. multi-user's bi-directional relaying transmission method as claimed in claim 6 is characterized in that: power division parameter δ _kMethod for solving comprise the steps:

Step 1 is established t _Max=min _{J, k}c _Jk/ d _Jk, t _Min=0;

Step 2, order $\hat{t}=\frac{t_{\max }+t_{\min }}{2};$

Step 3, solving-optimizing,

Step 4 is if following formula is found the solution the value that obtains less than P _R, then

Otherwise, establish

Step 5 jumps to step 3, until t _Max-t _MinLess than 0.01.

10. multi-user's bi-directional relaying transmission method as claimed in claim 6, it is characterized in that: in step 4, each user terminal deducts distracter with the signal that receives.

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